This invention generally relates to motors and stationary assemblies therefor and, in particular, film slot liners and end caps for insulating the slots of the stationary assembly of such a motor and for retaining the slot liners in the slots.
Motors include stator cores which are typically manufactured by bonding a number of steel laminations together. A number of teeth extend from the core of a motor to form slots between adjacent teeth. Coils of wire are wrapped around the teeth and through the slots in either a distributed or salient winding pattern. Thus, energizing the coils generates an electromagnetic field in the core for rotating a rotatable assembly of the motor. In order to generate the electromagnetic field and prevent shorting, it is necessary to electrically insulate the core from the coils of wire.
In addition to having slot insulators, present motors require the insertion of insulative wedges between the coils and the tips of the stator core's teeth. Wedges serve the dual purpose of insulating the tips of the teeth from the coils and retaining the coils in the slots. The use of wedges, however, impedes machine winding. As an alternative to wedges, some slot insulators include flaps which abut each other, or a single flap which abuts a side wall of the insulator, to cover the opening of the slot for retaining the wire in the slots during winding and for insulating at the tips of the teeth. Flaps of the present designs, however, tend to become wrapped under the wire during high volume machine winding. Therefore, present insulators are disadvantageously adapted to improved winding and high volume machine winding.
Further, present slot insulators include cuffs for covering the ends of the teeth and for retaining the insulators in the slots. Such cuffs, however, are disadvantageous to high volume machine production of the motor's stationary assembly because they impede wire control during machine winding of the stator core. Without the cuffs, though, present motors cannot easily retain the slot insulators in the slots for machine winding and the ends of the teeth are not insulated from the coils of wire.